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Space Elevators

Posted by: roygrif - Mon Aug 02, 2004 3:39 pm
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Space Elevators 
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Post    Posted on: Wed Aug 11, 2004 1:46 am
Herman Desmedt wrote:
Yes, if you keep thing limited to orbits.... but the point is that the maglev of this elevator can bring whatever payload also from LEO to escape velocity and that is far from a "tiniest bit".
See the picture ?


No joy, friend: Each action has an equal and opposite reaction. If the rail begins to accelerate the vehicle to delta-vee, the vehicle in turn will begin to accelerate the rail to delta-vee. Only way to stabilize the rail is to have an equal-power rocket burn. It'd reduce the actual vehicle mass, but it wouldn't save any on fuel.

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Post    Posted on: Wed Aug 11, 2004 2:08 am
spacecowboy wrote:
Herman Desmedt wrote:
Yes, if you keep thing limited to orbits.... but the point is that the maglev of this elevator can bring whatever payload also from LEO to escape velocity and that is far from a "tiniest bit".
See the picture ?


No joy, friend: Each action has an equal and opposite reaction. If the rail begins to accelerate the vehicle to delta-vee, the vehicle in turn will begin to accelerate the rail to delta-vee. Only way to stabilize the rail is to have an equal-power rocket burn. It'd reduce the actual vehicle mass, but it wouldn't save any on fuel.


I agree, and that is why additional thusters are needed to keep the elevator in place. The problem is to get the fuel from somewhere.

There is however another thing that keeps puzzling me and that might mean a gain anyway:
This elevator, just like an Earth-bound elevator is kept at geostationary rotation speed, which means 1 turn per day. This means that payloads do not need to be brought to LEO with a large horizontal speed but that a sub-orbital hop might do the job. An SS1 could "deliver" a payload. Reason enough to keep the project in mind.


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Post    Posted on: Wed Aug 11, 2004 2:29 am
So after reasoning, the project looks like this:
A space elevtor 72000 km in length, one end kept close to earth and it center of gravity in GEO, which means the other end is 36000 further than GEO. The whole thing is kept to geostanionary speed.

A suborbital hop right under this elevator delivers a payload and the elevator lifts this payload to wherever needed or launches it at escape velocity. To keep the elevator in place additional thrusters are needed.
The moon may deliver the necessary fuel for this.
After all, this means that the structure must support some gravitational pull, but anyway less than when starting all the way down from earth. In space this will anyway be easier to build than the earthbound version. Eventually, it may simply become an earthbound one.
A cable could be kept straight with two weights at either end, but a lightweight rigid structure (I wonder if steel or titanium tubes still will hold) is a better option.
I tried to do some calculations and using extreme lightweight tubes (hope that strength is right), it could be done with 480 shuttle flights or 100 Energya flights


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Post    Posted on: Wed Aug 11, 2004 12:33 pm
Hello, Mark Rejhon,

if I remember right, Edwards' Proposal includes a simple sounding protection measure against some damages and weaknesses of the nanocarbontube-cable: After the cable has reached the earth first epoxy will be painted around it by the first climbers to be used as part of the counterweight.

Concerning the other climbers to be used for transportation purposes I don't know wether Edwards is providing it but there might be another cable linked to the climber only as protection against falling down to earth's surface. If on the other side a climber will really fall down the cable to climb and the climber itself will move away from one another. So damaging by the climber may occur only by not properly fit wheels.

Additionaly there might be lasers and microscopic cameras inspecting the cable at each climb and for safety there will be a specified minimum state of the cable, its thickness and the epoxy. A computer will know these specifeid values and will compare them to the results of the camera and the laser. It will give warnings and it will stop all climbs if the situation will become serious. Then sophisticated specialists only will be able to move by the climber. As an alternative the climber might refresh the epoxy automatically at the dots where this is needed and give a message to the engineers.

There may be special inspection climbs.



Might that remove some sorrows? Or did I misunderstand something?



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Post elevator prize   Posted on: Sat Aug 28, 2004 12:30 am
here is a good article on an idea for a prize on building a space elevator

http://www.msnbc.msn.com/id/5792719/

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Post    Posted on: Tue Aug 31, 2004 8:54 am
I read it today under www.xprizenews.org - but I would not agree that the elevator will SSO etc. let look like being from yesterday.

The competition for tense of the tether may lead to tethers that could applied in space tourism. In this board are discussed some ideas depending on tethers and cables.

Burt Rutan's and Bigelow's plans could be developed further to constructions using tethers and cables. The first results of the elevator-prize this way may be tested concerning practical usability, In this case they would assist private space travels, cause revenues for the inventors and producers and provide informations concerning required improvements.



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Post    Posted on: Mon Oct 11, 2004 10:35 am
At the site of elevator:2010, www.elevator2010.org/site/index.html , there is a forum too. It looks like at least one of us here is discussing there too.

So we can and we should discus the space elevator only concerning the use it is providing: How to use it, what purpose for to use it, what scales are useful if we are talking about derivatives and so on.

What also might be discussed at this board is wether it makes sense for a XPRIZE team to compete for the elevator prize too or wether it does not make sense.



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